AS 4632:2020 pdf Over-pressure and under-pressure shut- of devices

AS 4632:2020 pdf Over-pressure and under-pressure shut- of devices
1.1  Scope
This Standard sets out requirements for over-pressure and under-pressure shut-off devices up to 150 mm nominal bore (DN 150) for use on natural gas (NG), simulated natural gas (SNG), town gas (TG),tempered liquefied petroleum gas (TLP) and liquefied petroleum gas (LPG), intended to be fitted in the gas supply downstream of the consumer billing meter or an LPG first stage pressure regulator.
The requirements apply to over-pressure and under-pressure shut-off devices intended for installation into consumer piping either directly or as part of a gas pressure regulator.
NOTE 1  Over-pressure shut-off devices generally serve to protect equipment downstream of regulators from being pressurized beyond its rated working pressure if the regulator fails.
This Standard does not cover devices incorporating automatic safety shut-off valves actuated by
electrical pressure-sensing devices.
NOTE 2  The requirements for pressure-sensing devices are covered in AS 4628 and the requirements for automatic shut-off valves are covered in AS 4629.
Conformance to the requirements of this Standard does not imply acceptability for use without
supplemental tests in an intended application.
NOTE 3  For over-pressure and under-pressure shut-off devices with flows greater than 200 m 3 /h for natural gas and town gas refer to EN 14382.
1.2  Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document:
NOTE  Documents referenced for informative purposes are listed in the Bibliography.
AS 2136, Method for detecting the susceptibility of copper and its alloys to stress corrosion cracking using the mercurous nitrate tests
AS/NZS 5601.1, Gas Installations, Part 1: General installations
AS/NZS 5601.2, Gas Installations, Part 2: LP Gas installations in caravans and boats for non-
propulsive purposes ISO 6957, Copper alloys — Ammonia test for stress corrosion resistance
1.3  Terms and definitions
For the purpose of this document, the following terms and definitions apply.
1.3.1 consumer billing meter
measurement device that is used to measure the quantity of gas transported through the gas
distribution network to a consumer (including other gas distribution network operator connections)
[SOURCE: AS/NZS 4645.1:2018]
1.3.2 gas
combustible fuel gas which may be one of the following.
1.3.2.1 liquefied petroleum gas
LPG
gas composed predominantly of any of the following hydrocarbons, or any combination of them, in the vapour phase: propane, propene (propylene), butane, butene (butylene)
1.3.2.2 natural gas
NG
hydrocarbon gas consisting primarily of methane
Note 1 to entry: Refer to AS 4564 for further information.
1.3.2.3 simulated natural gas
SNG
gas in air mixture comprising approximately 55 % commercial propane and 45 % air
1.3.2.4 tempered liquefied petroleum gas
TLP
gas in air mixture comprising approximately 27 % commercial propane and 73 % air
1.3.2.5 town gas
TG
gas manufactured from coal or petroleum feedstocks
1.3.3 may
indicates the existence of an option
1.3.4 metric standard condition
MSC
absolute temperature of 288.15 K (15 °C) and an absolute pressure of 101.325 kPa
1.3.5 over-pressure shut-off device
OPSO
device incorporated in the gas pipework system to shut off the supply of gas when the pressure at the sensing point rises to a set pressure
1.3.6 rated working pressure
maximum allowable inlet pressure specified by the manufacturer
1.3.7 regulator
device that maintains the outlet pressure constant within given limits, independently of the variation
in inlet pressure and/or flow rate
1.3.8 shall
indicates a statement is mandatory
1.3.9 should
indicates a recommendation
1.3.10 trip pressure
set pressure
pressure at which the device is intended to shut off the flow of gas
1.3.11 trip pressure range
range of pressures, as specified by the manufacturer, within which the device can be adjusted to trip
1.3.12 under-pressure shut-off device
UPSO device incorporated in the gas pipework system to shut off the supply of gas when the pressure at the sensing point falls to a set pressure